We walk you through the steps to replace a failing furnace flame sensor. This is one of the easiest furnace repairs, and one of the most common problems on gas furnaces. With a few simple tools, you can take charge and get your furnace in working order again.

1. Disconnect the Furnace

Shut off power at the power switch and close gas valve.

2. If Furnace Has Been Running, Allow 30 Minutes for Components to Cool Down

The components near the burner will be very hot. Allow 30 minutes after shutdown to allow the flame sensor and surrounding burner components to cool.

3. Remove Burner Compartment Door

Remove the panel. There will be twist locks on the burner compartment door, or screws securing the panel. Other furnaces, you may simply have to lift up on the door, and pull the bottom outwards to remove the door.

4. Locate Flame Sensor

The flame sensor will be near the burner. You can locate it by tracing the pipe from the gas valve upwards. The Flame sensor will be typically mounted at the last burner.

5. Remove Old Flame Sensor

Detach the flame sensor electrical lead. Some flame sensors will have a permanent attached lead wire that will need to be disconnected from the control board. Others will have a lead that detaches at the flame sensor.

The flame sensor will be attached by one or two screws. Unscrew the screws holding the flame sensor in. Compare the old flame sensor to the new one to ensure you have the correct one.

7. Install New Flame Sensor

Mount the new flame sensor. Some may come with a gasket and will be provided with the new part. Ensure that the flame sensor is the path of the flame to ensure proper function. Reattach electrical lead.

8. Install Furnace Doors

Reinstall the burner compartment door.

9. Turn On Furnace Switch and Gas

Open the gas valve and turn on power to the furnace. Observe for proper operation.

If you have any further questions on the repair process, or need help selecting the parts you need for this repair, contact us!

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